Open the More Blocks panel, click Add an Extension, and select Pi GPIO. You should then see two new blocks appear:
You can use these two purple blocks to control output pins or read input pins by entering the pin number into the field, or using a variable containing the pin number:
To control an LED connected to GPIO10, you can use these blocks:
Click the green flag, and the LED will blink on and off repeatedly.
To read the state of a button connected to GPIO10, you can use these blocks:
Note that the button is pulled up so the GPIO pin will read high when it is not pressed, and low when it is pressed.
To connect the LED and button together, you can use these blocks:
